A steering damper is fitted between the rotary handlebar of a vehicle and its fixed frame or chassis to dampen shocks and violent movements which are transmitted from the front wheel(s) to the handlebar. Where the steering damper is used on a motorcycle, it can also solve the problem of wobbling, which can occur in a motorcycle at high speeds. Wobbling means that the front wheel of the motorcycle begins to oscillate with increased amplitude about the steering axle. Where the steering damper is used on a four-wheeled all-terrain vehicle, a so-called ATV, the steering damper is primarily designed to dampen out the rapid steering movements caused by, for example, an asymmetric load upon the wheels.
The steering damper is not standard on all vehicles, but is a product which is suitable for retrofitting to improve the handling characteristics of the vehicle. Of course, an original fitting of the steering damper is also possible. Both when the damper is originally fitted and when it is retrofitted, it is an advantage if as few specially manufactured parts as possible need to be used.
In the prior art, for example in the Applicant's own product SD 410, which is a wing damper using technology drawn from U.S. Pat. No. 4,773,514, the damper body is fixed to the mounting brackets of the handlebar by means of a specially manufactured clamp. See prior art, FIG. 1, and detailed description in the specific part. The aim is for the center of rotation of the steering damper to coincide, when fitted, to the steering axle of the vehicle. The mounting bracket which connects the steering damper to the frame can be fixed in a number of different ways, depending on the motorcycle make, model and year.
This securement of the steering damper to the vehicle means a simple assembly, which can also be carried out by the end customer himself, and easily accessible adjusting knobs for modifying the damping characteristics.
Drawbacks with this mounting are that on modern-day motorcycles and ATVs there are no standard dimensions for the placement or diameter of the handlebar or for the distance between steering head and frame. A very large number of clamp versions are therefore needed to allow the damper body to be fitted.
The above-described assembly also results in the steering damper often being the highest point on the handlebar, which means that the steering damper can easily be damaged as a result of its placement.
Other known steering dampers are shown in, for example, EP 1291276, U.S. Pat. No. 4,773,514 and in WO 2005035349A.
In both EP 1291276 and U.S. Pat. No. 4,773,514, a rotation damper in the form of a wing damper is shown, in which the damper consists of a housing having a sector-shaped cutout in which a wing-shaped arm is rotated in a damping medium. Also present in the housing are channels, which can be adjusted to regulate the flow between the two chambers formed by the housing and the wing-shaped arm. In EP 1291276, the steering damper is mounted on the frame, substantially behind the handlebar, and the wing-shaped arm is connected to the rotary steering axle of the motorcycle via a protruding shaft. In U.S. Pat. No. 4,773,514, the steering damper is fixedly mounted on a fork crown of the motorcycle behind the handlebar and the center of rotation of the wing-shaped arm is via a mounting bracket consisting of a lever and an extension pin connected to the frame.
The placement of the steering damper behind the handlebar, yet with the center of rotation of the steering damper still coinciding with the steering axle of the motorcycle, is difficult to realize, due to lack of space, without modifying the fork crown. Moreover, the steering damper and its outer parts come so close to the driver that they can inconvenience him.
In WO 2005035349, a steering damper in the form of a double-armed wing damper is described, which is designed for use on a motorcycle in which the steering column, i.e. in this case also the steering axle, extends through its center and in which the fork crown is fastened in the steering column with a retaining nut. The steering damper is shown fitted both above (FIG. 3) and below the fork crown (FIG. 5). This double-armed wing damper does not have a lever for connecting the steering device to the frame, but rather the outer housing is directly fitted in the control column and the double-action wing is fixed directly in the control column. In FIG. 5, the rotary arms are connected to the rotary steering axle via a locking member and to the fixed frame via a clamping joint clamped around the steering column. The solution according to FIG. 5 requires specially manufactured parts, for example an extended steering column or a modified steering head, which adds to the costs involved in retrofitting the steering damper.
U.S. Pat. No. 5,927,740 shows another type of steering damper, which is integrated in the steering column. In this solution, the steering damper housing is fixedly built together with the steering axle and the moving internal parts of the damper are made to rotate by virtue of being connected to the frame and the steering column via an arm connected to the upper bearing device. Dampers fitted in the steering column involve the damper preferably being fitted in the vehicle already in the original production, with the result that the steering damper cannot be fitted as an extra accessory on a vehicle having a lower purchase price. Moreover, the pretensioning of the bearing device is complicated, since the whole of the steering damper is used as a force-producing member and a sufficiently precise pretensioning is difficult to achieve.